Minutes for meeting Mon, 18 January 1999 at 4pm EST.
Date: 18 January 1999
Time: 4:00 pm EST (2:00 pm Socorro, 2:00 pm Tucson)
Phone: (804)296-7082 (CV SoundStation Premier Conference phone).
Past minutes, etc on MMA Imaging and Calibration Division Page
Agenda
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Results of calculations of expected dynamic range and fidelity for various wavelengths and a few combinations of anomalous refraction and wind loading to see if the antenna RFP pointing specification of 0.7" is adequate for the sub-millimeter science we are proposing to do with the MMA. John has FAXed copies of his calculations to Peter at the AOC and Al in CV.
We had considerable discussion on several points. (1) In the calculation, the worst effects arose from the constant wind on the site. JL assumed that the amplitude of this global pointing error was half the total allowed offset pointing specification, or 0.5", independent of antenna diameter. Here we are concerned with the error which arises because the offset pointing source lies at a different azimuth and elevation than does our target source. As the telescope moves from one position to another, the direction of the wind with respect to the antenna does also, causing this problematic pointing error. In a full treatment, of course, this error is sensitive to the precise geometry of the antenna. There probably will be a diameter-sensitive component to the magnitude of this error. (2) The calculations were performed for three frequencies (100,300,900 GHz) and three antenna diameters (8, 10 and 12 m) for two quartiles of 'seeing', as defined in MMA Memo 223 (Holdaway and Woody). The magnitude of wind was taken as 9 m/s, the average daytime value. However, best seeing tends to occur at night, when winds are quite calm (2.5x lower in magnitude). Hence these first calculations are probably somewhat pessimistic about the Dynamic range and image fidelity under the best conditions. (3) Few science programs for the MMA list goals for dynamic range and image fidelity. The planetary group needs 100:1 image fidelity in the submillimeter which appears quite optimistic, even for an 8m telescope, at 900 GHz. It was decided that if Lugten can update his table to try to take into account (1) and (2), and for two values of pointing specifications for the antennas, it will be easier to decide if the existing pointing specification in the draft RFP is adequate.
The MAC said in November:
'It is unreasonable to expect all 9-10 receivers to be completed for 60 or more telescopes by the time the MMA/LSA comes on-line. Therefore the plan to install only three bands initially is reasonable. We recommend that two of the 3 bands should definitely be 90 GHz and 650 GHz. The third could be either 230 GHz or 345 GHz; compelling arguments for either can be made. The MAC favored 230 GHz over 350 GHz, but only marginally.
The remainder of the receivers should be installed as rapidly as possible. The MAC foresees a major operation installing more than 400 additional receivers, the logistics of which will have to be carefully planned. There should be a priority ordering of the subsequent bands to be installed as part of the plan of deployment and a time line should be worked out. The preferred sequence of receiver installation should be established on the basis of community input, either via the MAC and its European counter part or at the Science meeting next year. '
As I read this, the first priority for bands lies with 90-115, 230, 650, 350 GHz. That is, using the numbering and frequencis from MMA Memo 213,
Band No. 3, 89-116 GHz
Band No. 6, 211-275 GHz
Band No. 9, 602-720 GHz
Band No. 7, 275-370 GHz
The MAC seems to favor reserving judgment on the subsequent sequencing of receiver installation. I'll jump the gun and make a proposal. After that, I would recommend the order be
Band No. 2, 67-90 GHz
Band No. 4, 125-163 GHz
Band No. 5, 163-211 GHz
Band No. 8, 385-500 GHz
Band No. 1, 30-40 GHz
Band No. 10, 787-950 GHz
which I propose for a discussion topic at our Imaging and Calibration Meeting next week, and for the MAC, which might meet as scheduled 13 Jan.
Looks like the European-US meeting in Tucson may occur 21-23 Feb 1999. What MMA Imaging and Calibration tasks might the Europeans aid us in?
1. Investigation of 183 GHz phase correction systems. This would be a continuation of the current program, in which one 183 GHz radiometer is situated at each end of the 12 GHz interferometer baseline at Chajnantor.
2. Investigation of total power imaging modes. The continuing 'DREAM' mode and related modes at the JCMT, as well as characterization of 1/f noise in SIS receivers, could help us to understand problems associated with sensitive total power observing modes.
3. Soil sampling.
4> Configurations studies. There has already been sizable interest in this subject, resulting in several memos in the Memo Series.
Note that the 12m '30th birthday meeting' will be of substantial interest to our group:
6- 9 Jun 'Imaging at Radio through Submillimeter Wavelengths' meeting in Tucson
Text of a letter I sent to the proposed SOC of the September 1999 meeting:
As you may know, a meeting of U. S. and European scientists is being planned for the Fall of 1999 in Washington, D. C. The goal of the meeting is to review the scientific program planned for the joint array and how that program interacts with the science goals of other astronomical facilities expected to be operational at the time that the MMA/LSA becomes operational.
The time and venue of this meeting are planned for maximum impact on the Congress, as the United States portion of the MMA/LSA construction budget will be coming under consideration by the Office of the Budget and Congress during the period Fall 1999-Fall 2000.
In November, members of the U. S. Millimeter Array Advisory Committee (MAC) agreed to serve as the Scientific Organizing Committee (SOC) for this meeting. In expectation of a memorandum of understanding being signed by the European Negotiating Team for the LSA and NSF/NRAO before the meeting, I invite the members of the LSA Advisory Committee to join the SOC.
An excellent venue for the meeting has been found at the historic, neoclassical building housing the Carnegie Institution of Washington (http://sak.ciw.edu/) 1530 P Street, N.W. Washington, DC 20005 not far from the White House, the AAS, AUI or most embassies. The meeting will occur in the large auditorium (capacity about 400). Just outside the auditorium is a foyer which can accommodate poster papers. We anticipate attendance by between 100 and 200 scientists and officials at a meeting lasting two days.
Since maximum impact upon Congress and the budget are targets of the meeting, it should be held after the Labor Day holiday weekend (Sept. 4-6). The facility is available 16-17 September or 23-24 September. I suggest that 16-17 September might have less impact on University schedules, allowing more scientists to attend.
I invite your participation in the meeting and its planning. Please begin by commenting on the dates for the meeting, and with discussion on major topics to be addressed.
Anyway, I propose to get a list of available dates and nominate this whole bunch as the SOC, letting people decline to serve rather than offer to do so. The list of SOC members is therefore:
MAC:
John Bieging
Geoff Blake
John Carlstrom
Ed Churchwell
Ewine van Dishoeck
Neal Erickson
Neal Evans
Mark Gurwell
Richard Hills
Gill Knapp
Jim Moran
Luis Rodriguez
Pete Schloerb
Jean Turner
Eric Wilcots
SAC:
Karl Menten
Roy Booth
Stephane Guilloteau
Malcolm Walmsley
Peter Shaver
with Ewine and Richard on both committees. I will CC:
Masato Ishiguro
Wootten has constructed a prototype WWW page for the meeting at:
Science topics for this suggestion were drawn from those identified by
the 1997 Thaddeus committee (Task Group on Space Astronomy and Astrophysics,
Committee on Astronomy and Astrophysics, Board on Physics and Astronomy, Space
Studies Board, Commission on Physical Sciences, Mathematics and Applications,
National Research Council) report
A New Science Strategy for Space
Astronomy and Astrophysics". I further limited them to those for which
I thought that the MMA would provide deep impact. Modifications and suggestions
are welcome.
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T. Helfer:
A. Wootten: 3-6 Feb (12m observing) 8-9 Feb (MMA talk at SPECS conference) 16 Feb (43m observing)
J. Mangum:
M. Yun:
B. Butler:
S. Radford:
Action Items 18Jan99
Travel